There have been difficulties in mounting thinner semiconductor chips and 3D mounting with conventional liquid underfill film materials. For this reason, use of pre-applied underfill film (PUF), in which an underfill film is pasted onto a substrate before metal bonding or compression bonding electrodes of a semiconductor IC (integrated circuit) to electrodes of a substrate, has been investigated.
Mounting methods of using such a pre-applied underfill film are performed, for example, as described below (for example, see PLT. 1).
Step A: Paste underfill film to a wafer and dice the wafer to obtain semiconductor chips.
Step B: Align the semiconductor chip on the substrate.
Step C: Compression bond the semiconductor chip and substrate together at a high temperature and pressure; thus, metallic bonding of solder bumps ensures electrical conduction and curing the underfill film bonds the semiconductor chip to the substrate.
As a method for improving per-chip production takt time, multi-head or collective bonding has been proposed. However, multi-head devices are expensive and would increase per-chip cost. Furthermore, in collective bonding, because temperature control with the bonder (heat tool) has been difficult, differences in temperature-increase rates depending on chip position have led to bonding defects such as void generation and resin being sandwiched between bumps.